Opened 7 years ago

Closed 7 years ago

#4681 closed defect (invalid)

Export scale does not match exported file

Reported by: bubaya Owned by: rails-dev@…
Priority: minor Milestone:
Component: website Version:
Keywords: scale export Cc:

Description

Given the following example: http://parent.tile.openstreetmap.org/cgi-bin/export?bbox=5.0,50.0,5.1,50.016666&scale=10500&format=pdf

This map extract is 1' lat high, this is 1852m. The scale is 1:10500. Hence, the exported pdf should be 17,64cm high. In fact, it is 34,6cm high; that means a scale of 1:5353.

The same problem if I export images: When I export the same area as a PNG image, the image is 981px high, and has a resolution of 72ppi. That means a height of 34,6cm, the same as the PDF. To match the 1:10500 scale, the image would have to have a resolution of 141.3ppi. If I play around, I do not get a constant resolution that would match the scale, but always value between 140 and 145ppi.

Change History (1)

comment:1 Changed 7 years ago by Tom Hughes

Resolution: invalid
Status: newclosed

We are entirely dependant on mapnik here, so any issue will be with mapnik and not with us.

IIRC mapnik works to 96dpi so that is what I would expect the scale to be based on.

Last edited 7 years ago by Tom Hughes (previous) (diff)
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